The functions $p(x),$ $q(x),$ and $r(x)$ are all invertible.  We set
\[f = q \circ p \circ r.\]Which is the correct expression for $f^{-1}$?

A. $r^{-1} \circ q^{-1} \circ p^{-1}$

B. $p^{-1} \circ q^{-1} \circ r^{-1}$

C. $r^{-1} \circ p^{-1} \circ q^{-1}$

D. $q^{-1} \circ p^{-1} \circ r^{-1}$

E. $q^{-1} \circ r^{-1} \circ p^{-1}$

F. $p^{-1} \circ r^{-1} \circ q^{-1}$

Enter the letter of the correct expression for $f^{-1}.$
Explanation: Let $y = f(x) = q(p(r(x))).$  Applying $q^{-1},$ we get
\[q^{-1}(y) = p(r(x)).\]Applying $p^{-1},$ we get
\[p^{-1}(q^{-1}(y)) = r(x).\]Finally, applying $r^{-1}(x),$ we get
\[r^{-1}(p^{-1}(q^{-1}(y))) = x.\]Hence, $f^{-1} = r^{-1} \circ p^{-1} \circ q^{-1}.$  The correct answer is $\boxed{\text{C}}.$